(a) Field of the Invention
The invention relates to an umbrella structure, and more particularly, to an umbrella structure, which overcomes drawbacks in the existing state of the art which is incapable of securely locking the fastening orifice after reducing the volume of the umbrella.
(b) Description of the Prior Art
With reference to FIGS. 1 and 1A, a prior umbrella comprises a cover 11, a shaft 12, a notch 13, a runner 14, main ribs 15 and stretchers 16. Around the notch 13 is a plurality of pivotally disposed main ribs 15 for supporting the cover 11, whereas around the runner 14 is a plurality of pivotally disposed stretchers 16 for supporting the main ribs 15. The shaft 12 is in a two-sectional or three-sectional form, and has a top end thereof fixed to the notch 13. The notch 13 is fastened with an inner tube 122, which has a rectangular fastening orifice 121 at an appropriate position for setting free a fastening button 17 disposed at the inner tube 122. The inner tube 122 is also penetrated through the runner 14, so as to allow the runner 14 with up-and-down sliding movements. When the umbrella 1 is stretched, the runner 14 is pushed upward to the fastening button 17 that further butts against a bottom portion of the runner 14, such that the main ribs 15 prop up the entire cover 11. The umbrella 1 is collapsed by pressing the fastening button 17.
As described above, although the prior umbrella 1 fulfills stretching and collapsing functions, a collapsed volume thereof is rather large because the shaft 12 is a two-sectional or three-sectional structure. The collapsed umbrella 1 is only suitably stored in larger handbags or backpacks but not in commonly used handbags. To reduce the volume of the umbrella 1, it is necessary to devise the shaft 12 as a multi-sectional design, with a difference between diameters of an outer tube and the inner tube of the shaft 12 being inevitably enlarged. When stretching the umbrella, a substantial space is left between the inner tube having the smallest diameter and the runner 14 having a diameter larger than that of the outer tube, so that undesired wavering of the shaft 12 relative to the runner 14 is resulted. Also, the fastening button 17 becomes unsecurely butted against the runner 14, and hence it is likely that the runner 14 fails to be firmly stretched for being frequently slipped off in a downward direction.
Referring to FIGS. 2 and 2A showing another prior umbrella 2, a shaft 22 is devised as a four-sectional or five-sectional design for reducing the volume of the umbrella 2. As appropriate, one or two ends where stretchers 25 come into contact with a runner 23 are inserted and extended with extension posts 27. When stretching the umbrella 2, the shaft 22 is upheld by the extension posts 27 through the runner 23 to keep the shaft 22 from undesired wavering. A fastening button 26 at the shaft 22 and a bottom portion of the runner 24 are allowed with a larger mutual supporting plane, thereby enabling the stretchers 25 connected with the runner 23 to prop up main ribs 24 that further stretch an entire cover 21. The umbrella 2 is collapsed by pressing the fastening button 26.
As described above, the prior umbrella 2 advances over the prior umbrella 1 by having a smaller volume. However, due to the extension posts 27 in the prior umbrella 2, pushing movements of the runner 23 are made unsmooth and unhandy since the shaft 22 is butted by the extension posts 27 when stretching the umbrella 2.
Referring to FIGS. 3 and 3A showing yet another prior umbrella 3, a shaft 31 is devised a multi-sectional design. At an appropriate position where an outer tube 312 of the shaft 31 is fixed to a notch 32, the shaft 31 is provided with a rectangular fastening orifice 311. An elastic fastening button 34 is also disposed for coordinating with one side of a runner 33, so as to complete stretching and collapsing of the umbrella 3. The elastic fastening button 34 has one end thereof formed as a hook portion 341, and the other end thereof formed as a pressing plane 342. Underneath the pressing plane 342 is a spring 343. When stretching the umbrella 3, the runner 33 is pushed upward, and the rectangular fastening orifice 311 provided at the outer tube 312 is locked by a hook portion 341 of the elastic fastening button 34 at the runner 33. When collapsing the umbrella 3, by pressing the pressing plane 342 at one end of the elastic fastening button 34, the hook portion 341 is disengaged from the rectangular fastening orifice 311 due to actions of the spring 343, thereby collapsing the umbrella 3.
As described above, although the elastic fastening button 34 of the prior umbrella 3 also fulfills stretching and collapsing functions of the umbrella 3, the issue of a fastening button being incapable of securely locking the runner due to a reduced volume of the umbrella remains unsolved. Therefore, in the view of the aforesaid drawbacks, it is a vital task of the invention to provide an umbrella structure, which not only overcomes the aforesaid drawbacks but also offers usage conveniences as well as industrial values.